Boosting the performance of thermoelectric polymers by molecular alignment

Thermoelectrics (TEs) are energy harvesters that convert waste heat into electrical energy and vice versa (they can use electricity to provide active heating/cooling). Among the different classes of TE materials, organic TE materials present the advantages of being non-toxic, abundant, printable and mechanically flexible. Therefore, organic thermoelectrics (OTEs) are perfect candidates to power wearable autonomous sensors integrated in smart textiles or even in direct contact with the skin. Such systems can find multiple applications in biomedicine and sports. However, the current performance of OTEs lags behind the performance of its inorganic counterparts. Molecular alignment has been shown to affect strongly the properties of electronic polymers. Therefore, in this project, the candidate will work on inducing molecular alignment on OTE materials using an external electric field. The hypothesis of this project is that the Electric Field Assisted Molecular Alignment (EFAMA) technique will result in materials with well aligned molecules leading to a boost in their TE performances. The correct measurement of the TE performance of organic thin-film materials is a challenging task. Hence, it will occupy an important part of this project. In this project, the PhD candidate is expected to: • Familiarize him/herself with the concepts of electrical conductivity and mobility, charge carrier concentration, Seebeck coefficient and thermal conductivity, and with the different methods to measure these properties. He/she will be required to master the use of commercial tools to measure these properties and, in some cases, to develop specialized setups. • Build a blade coating/solution shearing setup to apply EFAMA on thin films of OTE materials casted from solution using both commercial and customized (semi)conducting polymers with known TE properties. • Work in close collaboration with project mates for the morphological characterization of the films. • Thoroughly characterize the TE properties of the films and evaluate the effect of the e-field characteristics (AC vs DC, frequency and amplitude) on the final performance. • Correlate TE performances with molecular alignment to validate the project hypothesis. Extend the methodology to EFAMA 3D printed thick materials.